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The paper presents the possibility of using barium-selective electrode to a potentiometric determination of sulfates in silicic and aluminosilicate fillers. The results of sulfates potentiometric titration in silicic and aluminosilicate fillers are described. A statistical interpretation of the results was carried out. The recommended method is based on the end-point detection of sulfates potentiometric titration in hydro-alcoholic medium by means of barium chlorate(VII) titrant. The potentiometric titration, which uses an ion-selective electrode as the indicator for the end-point was applied as the analytical technique. The parameter ranges for accurate sulfates determination in model solutions and the method of samples' preparation for analysis were investigated.
EN
A potentiometric titration method (PT) and a stopped-flow kinetic technique monitored by a UV−Vis spectroscopy have been used to characterize the stability of series of Co(II)- and Ni(II)-thiodiacetato complexes, M(TDA), in the presence of 1,10-phenanthroline (phen) or 2,2’-bipyridine (bipy) in aqueous solutions. The stability constants of the binary (1:1), ternary (1:1:1) as well as the resulting hydroxo complexes were evaluated and compared to the corresponding oxydiacetate complexes. Based on the species distribution as a function of pH the relative predominance of the species in the system over a pH range was discussed. Furthermore, the kinetic measurements of the substitution reactions of the aqua ligands to phen or bipy in the coordination sphere of the binary complexes M(TDA) were performed in the 288–303 K temperature range, at a constant concentration of phen or bipy and at seven different concentrations of the binary complexes (0.2–0.5 mM). The kinetic stability of the M(TDA) complexes was discussed in relation to the experimental conditions and the kind of the auxiliary ligands (phen/bipy). Moreover, the influence of the type of primary ligand (thiodiacetate/oxydiacetate) on the substitution rate of the auxiliary ligands was also compared.
EN
The influence of a kind of support electrolyte on the ionic polyamino acids adsorption at the chromium (III) oxide – polymer solution interface was investigated. The NaCl and CaCl2 were used as the background electrolytes. In order to determine the effect of the electrolyte, the same value of ionic strength of the test solutions were taken. It was proved that formation of intermolecular and intramolecular complexes in the presence of divalent calcium ions is responsible for essential changes in polymer adsorption. Related to the ionic character of polyamino acid two different adsorption behaviours can be observed. The increase of the ASP adsorption amount in the presence of calcium ions may be explained by formation of complexes between the dissociated carboxylic groups and Ca2+ ions. The opposite situation takes place in the case of polylysine – the application of CaCl2 results in the dramatic decrease in the polymer adsorption caused by blocking the active sites available for LYS macromolecules. In order to make a comprehensive analysis, the zeta potential and surface charge density measurements were performed taking into account the kind of the background electrolyte. The above-mentioned tests were carried out in the absence and presence of the polyamino acid at two different concentrations – 10 and 100 ppm respectively.
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